Brief Introduction to SWIMS

Simultaneous-color Wide-field Infrared Multi-object Spectrograph, or SWIMS, is capable of

  • simultaneous imaging/spectroscopy of 0.9-1.4 and 1.4-2.5 μm wavelength ranges
  • imaging of maximum φ9.6 arcmin FoV (6.6 × 3.3 arcmin^2 on Subaru)
  • having a unique set of 8 medium-band and 6+4 narrow-band filters (e.g. SWIMS-18 survey)
  • multi-object (max ∼ 40 objects) slit spectroscopy with R ∼ 1000
  • integral-field spectroscopy with FoV of 18 × 14 arcsec^2


  • on TAO 6.5m telescope, large amount of observing time with excellent atmospheric window is available.
SWIMSComponent Assembly

Instrument Papers


Detector Control

Multi-Object Spectroscopy Unit (MOSU)

Integral Field Spectroscopy Unit (IFU)

Field of Views

Field of view (FoV) of the telescope is covered with multiple HAWAII-2RG arrays (λ_{cut}=2.5 μm, ∼ 0.2-mm or ∼ 10-pixel gap between arrays).

Imag. FoVφ9.6' (∼ 8.6' × 8.6')6.6' × 3.3'
Spec. FoV3.7' × 8.6'2.8' × 3.3'
# of arrays per arm4
(4096 × 4096 pixles)
(4096 × 2048 pixels)
Pixel scale (arcsec/pix)0.1260.095
Array configurationfov_blue_tao.png

Light-shaded regions show the FoV for the imaging mode while dark-shaded regions for the spectroscopy mode (for full range of spectra).

Black dots represent positions of source in the imaging mode which are also equivalent to the spectral positions of undeviated wavelength (λ ∼ 1.027 μm for blue, ∼ 1.734 μm for red).

Each stripe indicates the full range of the spectrum obtained (from shorter on the left to longer wavelength on the right). Note that any optical aberrations are not considered which would make the spectrum slightly broaden.

Available filters/grisms

Blue (0.9-1.4 μm)Red (1.4-2.5 μm)
Broad-bandY (λc=1.027, Δλ=0.096 : fileplot), J (1.251, 0.167 : fileplot)H (1.644, 0.291 : fileplot), Ks (2.139, 0.313 : fileplot)
Medium-bandJ1 (1.174, 0.118 : fileplot), J2 (1.294, 0.123 : fileplot)H1 (1.502, 0.121 : fileplot), H2 (1.617, 0.116 : fileplot), H3 (1.735, 0.117 : fileplot), K1 (2.023, 0.138 : fileplot), K2 (2.170, 0.140 : fileplot), K3 (2.314, 0.128 : fileplot)
Narrow-bandNB1244# (1.244, 0.015 : fileplot), NB1261# (1.261, 0.016 : fileplot), Paβ (1.294, 0.038 : fileplot), Paβ-off (1.329, 0.033 : fileplot)NB1630# (1.630, 0.017 : fileplot), NB1653# (1.652, 0.016 : fileplot), Paα (1.876, 0.022 : fileplot), Paα-off (1.948, 0.036 : fileplot), NB2137# (2.133, 0.021 : fileplot), NB2167# (2.164, 0.022 : fileplot)
GrismzJ (2.40 Å/pix, R ∼ 700-1200 w/ 0.5" slit)HKs (4.57 Å/pix, R ∼ 600-1000 w/ 0.5" slit)

Filters followed by "#" are those for SWIMS-18 survey. Requests for use for any other purpose will be also welcomed.

Transmission curves

ASCII data for each filter transmittance :

Integral Field Spectroscopy Unit

A compact & lightweight image-slicer IFU will be installed into the MOSU cryogenic storage.

Note that the following parameters may be subject to be changed.

λ (μm)0.9-1.4 (blue) & 1.4-2.5 (red)
R (=λ/Δλ)900-1400 (blue), 700-1200 (red)
FoV18.4" × 13.7"14.0" × 5.2"
# of slice2613
Slice width0.5"0.4"

Multi-object Spectroscopy Unit

The cryogenic storage called the carousel have 23 slots for night observations. Of them, several kinds of engineering-use masks and long-slit masks (one slot each), and one IFU module (occupying two slots) will be exclusively assigned. Other (∼ 15) slots can be used for users' MOS masks.

The time required to exchange from one mask to another is about 2.5 minutes (and additional 5 seconds/slot to rotate the carousel). The time for target acquisition will be measured on the telescope during engineering nights.

Detector Performance

We utilize an ASIC, called SIDECAR, and its interface board, JADE-2, which control all of readout functions, to efficiently operate Teledyne HAWAII-2RG 2048 × 2048 HgCdTe? infrared array.

Under cryogenic condition (∼ 77K), the detector performance has been assessed, as listed below.

Minimum Exposure Time1.48 sec
Dark Current< 0.05 e-/sec/pix
Readout Noise∼ 20--25 e- (CDS)
∼ 3--5 e- (32 Fowler)

Integrated performance (e.g., simulateneous control of multiple arrays, influences of other peripherals on readout noise, etc.) is currently being investigated.


Total throughput including the telescope is estimated to be ∼ 0.4 for imaging and ∼ 0.3 for spectroscopy.

Expected sensitivities (AB mag) on the Subaru telescope are calculated with assumptions of seeing size=0.5 arcsec (photometry aperture radius=0.5 arcsec for point source or spatial extent=5.0 arcsec for extended source), exposure time=1 hr, and S/N=5.

Sensitivities on the TAO 6.5-m telescope are supposed to be ∼ 0.3 mag shallower due to smaller light-collecting area.

Note that these values may change according to the background conditions of OH airglow and thermal emission.

  • Imaging
    Point source [mag]Y=25.2, J=24.9, H=24.2, Ks=24.4J1-2~25.0, H1-3~23.7, K1-3~24.0
    Extended source [mag/arcsec^2]TBWTBW
  • Spectroscopy (slit width=0.5" assumed, no binning applied along wavelength direction)
    Point source (mag)J=21.1, H=20.7, Ks=20.9
    Extended source (mag/arcsec2)TBW

Current Status

Coming soon.

Development Timeline

Coming soon.

添付ファイル: fileswims-mbfilter.jpg 16件 [詳細] fileswims-nb1630.jpg 52件 [詳細] fileswims-nb1244.jpg 45件 [詳細] fileswims-h.jpg 42件 [詳細] fileswims-ks.jpg 43件 [詳細] fileswims-nb1653.jpg 41件 [詳細] fileswims-nb2137.jpg 42件 [詳細] fileswims-k3.jpg 42件 [詳細] fileswims-nb1945.jpg 41件 [詳細] fileswims-nb1875.jpg 39件 [詳細] fileswims-k2.jpg 36件 [詳細] fileswims-filter.jpg 15件 [詳細] fileswims-h3.jpg 41件 [詳細] fileswims-h2.jpg 38件 [詳細] fileswims-nb2167.jpg 43件 [詳細] fileswims-j2.jpg 36件 [詳細] fileswims-nb1292.jpg 48件 [詳細] fileswims-k1.jpg 38件 [詳細] fileswims-h1.jpg 39件 [詳細] fileswims-j.jpg 45件 [詳細] fileswims-nb1261.jpg 39件 [詳細] fileswims-j1.jpg 44件 [詳細] fileswims-nb1326.jpg 47件 [詳細] fileswims-y.jpg 43件 [詳細] 33件 [詳細]

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Last-modified: 2020-07-30 (木) 20:37:44